Electron-discharge apparatus



. 1,614,154 Jan. 11 1927. f w. PIKE v I ELECTRON DISCHARGE APPARATUS Filed March 2, 1925 Inventor: OrisW. Pike His Afrorneg.

Patented Jan. 11, 1927.

UNITED, STATES,

PATENT OFFICE.

OTIS W. PIKE, OF SCHENECTADY, NEW YORK. ASSIGNOR TO GENERAL ELECTRIC I COMPANY, CORPORATION OF NEW YORK.

I ELECTRON-DISCHARGE APPARATUS.

Application filed March 2, 1925. Serial No. 12,491.

present invention relates to electron discharge apparatus, and more particularly to devices of the thermionic type having at least four electrodes.

One of the objects of my invention is. to provide an improved method for operating a device of the type mentioned and a new circuit organization whereby this method may be carried out.

In connection with electron discharge devices ofthe thermionictype having a grid for controlling the flow of current between cathode and anode, it has been proposed to em by a second grid between the cathode and the control grid, and to impress upon this second grid a constant positive potential somewhat lower than that of the anode. A gr d used in this way is commonly known as a space charge grid. The purpose of this grid is to lower the impedance between the cathode and anode, and .for this purpose the grid has ordinarily been maintained at a constant positive potential. 1

When such a device is used for the purpose of producing oscillation or, for example, as

a power amplifier inv such a way that the anode current may at times fall to a low value, it is not necessary to maintain the positive potential on the space charge grid at all times, it being suflicient. for all practical urposes merely to have the desired .posit1ve.potential on the grid at times when the current flowing to the anode is com ,paratively large. When the space charge grid is positive it is drawing current and consuming energy.

A more specific object of my invention is to provide a means for automatically varying the potential of the space charge grid in such a way. that it will be of such a ositive value as to appreciably lower the lmpedance of the device only when the current flowing to the anode is appreciably above its minimum value. At other times vthe space charge gridmay be .maintained at zero potential with respect to the cathode,.

or even at a negative potential without interfering with the satisfactory operation of the device, and by this exped ent the losses in the tem may be reduced and theefliciency t ereby increased. 1

The novel featureswhich I believe to be,

characteristic of my invention'are, set forth with particularity in the appended claims.

My invention itself, however, both a'sito its" system shown in Fig. 1 the control grid cir-- cuit is tuned by means of inductance 6, and variable'capacity 7. Oscillations will be generated and supplied from the plate or output circuit through a coupling transformer 8. The circuit between cathode and space charge grid 5 is coupled to the control grid circuit by means of the variable coupling 9. In order to adjust the phase of the potential impressed upon the circuit of the space charge grid, a variable condenser 10may be connected in shunt to the secondary of the coupling 9.

In this arrangement no positive bias need be supplied to the space charge grid. The potential applied to the space charge grid through the coupling 9 may automatically be adjusted so that it will be of a maximum positive value when the current flowing to the plate is maximum. The neu-- tralization of spacecharge efiect, 'of course, varies with this arrangement, but it may be caused to vary 1n nverse proportion to the current flow between cathode and anode.

When no current is flowing, the space charge grid'may be made negative so. that under these conditions it will not takeany cur rent or absorb anyvpower from the system.

'In the arrangement shown in Fig. 2, the device 1 is employed to amplify current supplied from the input coil 11 to thecircuit of the control grid 4. The circuit ofthe space chargejg'rid 5 may also be coupled to the control grid circuitby means of a variable coupling'12, and the space charge reduced in the samemanneras in the arrangement shown in Fig. '1. v

While I have shown and described only two embodiments of my invention, it will be apparent that many modifications in the circuit arrangements employed may be made without departing from the scope'ofmy invention as set forth in the appended claims.

' space between the cathode and the grid near- What I claim as new and desire to secure by Letters Patent of the United States, 1s:-- 1

'1. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between-cathode and anode, one of said grids being nearer the anode than the other and each grid having an independent connection to the cathode, of means for impressing al ternating potentials of substantially the same phase upon both of said grids.

2. he combination with an electron discharge" device having an electron emitting cathode, an anode and two gridsv interpose between cathode and anode, one of said grids being nearer the anode than the other, of means for impressing an alternating potential upon the grid nearest the anode to thereby effectively control the current flowing between cathode and .anode and means for neutralizing the space charge in the est the anode in inverse proportlon to the current flowing between cathode and anode.

3. The combination with an electron discharge device having an electron emitting cathode, an an de and two grids interposed between cathedE and anode, one of said grids being nearer t e anode than the other, of means for impressing an alternating potential u on the grid nearest the anode to thereby e ectivel tween catho e and anode and means for impressing an alternating potential upon the grid nearest the cathode and thereby varying the space charge in the vicinity of the cathode in inverse proportion to the current flowing between cathode and anode.

4. The combination with an electron discharge device having an electron emittin cathode and anode and two grids interpose between cathode and anode, one of said grids being nearer the anode than the other, of means for impressing an alternating potential upon the grid nearest the anode to thereby effectively control the current flow between cathode and anode and means for impressing an alternating potential of the same frequency upon the grid nearest the cathode.

5. The combination with an electron dis charge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said, grids being nearer the anode than the other, of

means associated with the grid nearest the anode arranged to produce alternating currents by the action of the device and means for impressing upon the grid nearest the cathode alternating potentials of such phase as to reduce the space charge in the vicinity of the cathode in inverse proportion to thecurrent flowing between cathode and anode.

6. The combination with an electron discharge device having an electron emitting control the current flow becathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of clrcuits connecting the cathode and each of the other electrodes, said.circuits being arranged to produce alternating currents by the control action of the grid nearest the anode and a coupling between the circuits of the two gridsr 7- The combination" with'an electron discharge device having an; electron emitting cathode, an anode and two grids interposed. between cathode and anode, one of said grids being nearer the anode than the other, of

d circuits connecting the cathode and each of.

the other electrodes, said circuits being arranged to produce alternating currents by the control .action of the grid nearest the anode and a coupling between the circuit of the grid nearest the cathode and one of the other circuits.

8. The combination with an electron discharge device having an electron emitting cathode, an anode and two grids interposed between cathode and anode, one of said grids being nearer the anode than the other, of circuits connecting the cathode and each of the other electrodes, said circuits being arranged to produce alternating currents by the control action of the grid nearest the anode, a coupling between the circuits of the two grids for impressing alternating potentials upon the rid nearest the cathode and means for' regu ating the phase of'the potentials im ressed upon that grid.

. posed between cathode and anode, which consists in controlling the flow of current between cathode and anode by impressing a controlling potential upon-the grid nearest the anode and impressing upon the grid nearest the cathode a potential of such value that the space charge in the device is neu- 1 tralized in inverse proportion to the current between cathode and anode.

10. The method of operating an electron discharge device having an electron emitting cathode, an anode and two grids intern5 posed between cathode and anode which consists in controlling the flow of current between cathode and anode by impressing a controlling potential upon the grid nearest the anode and impressing upon the grid nearest the cathode a variable potential of such phase relation with respect to the potential of the controlling grid that the space charge in the device will be reduced to a minimum value when the controlling grid 1 permits the maximum flow of current to the anode.

In witness whereof,'I- have hereunto set my hand this 28th day of February, 1925.

. OTIS W. PIKE. 

